spi: dw-mmio: Clock should be shut when error occurs

spi: dw-mmio: Clock should be shut when error occurs

BugLink: https://bugs.launchpad.net/bugs/1848046
[ Upstream commit 3da9834d9381dd99273f2ad4e6d096c9187dc4f2 ]

When optional clock requesting fails, the main clock is still up and running,
we should shut it down in such caee.

Fixes: 560ee7e91009 ("spi: dw: Add support for an optional interface clock")
Cc: Phil Edworthy <phil.edworthy@renesas.com>
Cc: Gareth Williams <gareth.williams.jx@renesas.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Gareth Williams <gareth.williams.jx@renesas.com>
Link: https://lore.kernel.org/r/20190710114243.30101-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>